Belgian Pat. No. 828,074 teaches the use of a catalyst containing phosphorus, molybdenum, bismuth, copper, at least one of Fe, Ni, Co, and K, and optionally, Li, Na, Rb, Cs, Be, Mg, Ca, Sr, or Ba in the preparation of maleic anhydride from butene-1, butene-2, butadiene, pentane, pentadiene, cyclopentadiene and benzene. Comparative Example 4, at pages 20 and 21 of this patent exemplifies that use of a catalyst having the formula P.sub.1.00 Mo.sub.12 Bi.sub.0.36 Cu.sub.0.54 O.sub.39.6 in the oxidation of butene-1 gave a 27.9% yield of maleic anhydride, based on the amount of butene-1 fed.
French Pat. No. 1,601,955 teaches use of a catalyst having the composition AO.sub.3 --B.sub.2 O.sub.5 --M.sub.2 O.sub.5 --N.sub.x O--R.sub.2 O wherein A is Cr, Mo, W or U; B is V or Nb; M is P, As, Sb or Bi, N is Cu, Ag, Fe, Co or Ni; R is Li, Na, K, Cs or Rb. Preferred composition is 15-55 atomic %A, 30-70% B, 0-15% M, 0.1-20% N, and 0-15% R.
The present invention is a result of a search for more efficient catalysts for use in the oxidation of 1,3-butadiene to produce maleic anhydride.
The catalysts employed in the present invention are unexpectedly advantageous in the production of maleic anhydride from n-butene, n-butenes and 1,3-butadiene. Especially desirable yields of maleic anhydride are obtained from 1,3-butadiene using the catalysts of the invention.